Answer
$x=10000$
Work Step by Step
If the number of sales a week is $x$, then the commission is $0.05x$
Then the equation is $300+0.05x=800\\0.05x=500\\x=10000$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.